Factors affecting the rate and pattern of the first costal cartilage ossification.

In the present study, the extent of costochondral ossification of the first rib was determined from 78 chest roentgenograms of 13 healthy male soldiers subjected to a periodic follow-up. Roentgenography was performed at a mean interval of 2.9 years over a 15-year period. Mean subject age was 24 years at the commencement of the study and 37 years at its termination. Our results show that ossification of the first costal cartilage may start early in adult life and progress at individual rates. The ossification process proceeded from the costal toward the sternal end of the cartilage in an anteromedial direction. The morphological age-related changes ranged from the formation of small osseous islands in the cartilage to a complete ossification between the first rib and the sternum. The main conclusion of the study is that the degree of ossification of the first costal cartilage as an indicator of age does not provide the precision necessary for anthropological or forensic studies.